A conceptual master plan to transform an old industrial site along the Lehigh River into a new neighborhood of offices, apartments, restaurants, shops, open space and parking decks was presented to the Allentown Planning Commission Tuesday afternoon.

Simply named The Waterfront, that $275-million neighborhood will be created on nearly 27 acres, the former Lehigh Structural Steel property beneath the west end of the Tilghman Street Bridge.

The property includes more than a half-mile stretch of riverfront and its developers promise direct public access to the Lehigh.

Ten new buildings are proposed for the site, plus two multi-level parking garages. Both the northernmost and southernmost office buildings fronting the river will be eight stories tall. The other buildings will be four or five stories tall, although the number of floors could change later in the planning process.

“Today is a very early look at these plans,” said Michael Hefele, the city’s planning director. “We have not finished a total staff review on this yet.”

Hefele told the planning commission no action will be taken on the conceptual plan until January, when that review is completed. He said the commission has 90 days to act on the plan from the date of submission, which was “just a week or so ago.”

“Our submission of the master plan is the start of the land development approval process,” explained developer Ryan Dunn in a statement released after the presentation.

“We will be submitting our fully engineered plans to the city and other regulatory agencies in the next few months,” added developer Andrew Twiggar. “We anticipate starting construction in 2014, with initial occupancy expected during early 2015.”

Hefele said after the commission acts on the master plan, the developers will submit a tentative plan, which is similar to a preliminary land development plan and contains more detail. He said a formal public hearing must be held on that tentative plan, adding the commission would act on that plan within 60 days after holding a public hearing.

For final plan approval, the developers can come in with just one phase of the project at a time, Hefele explained, then return with subsequent phases as development proceeds. The developers intend to first focus on that section of the property south of Tilghman Street, according to Twiggar.

The project was described for the planning commission by Robert Keppel of Cope Linder Architects in Philadelphia. He said all the old industrial buildings on the property will be removed.

Five-story-tall buildings will flank both sides of the west end of Tilghman Street Bridge. If those buildings were too short, people on the bridge would be looking at mechanical equipment on their roofs, said Keppel, and if they were too tall they would seem to be crowding the bridge. He said a person looking out from inside the fourth floor of those buildings will be nearly at eye level with someone walking across the bridge.

Furnace and Allen Streets will be extended all the way to the river and a new street, called Waterfront Drive, will run between them through the property. Keppel said all streets will be lined with trees and street lights.

A new service road will parallel the railroad tracks to serve the two parking structures and loading docks.

The developers plan 172 apartment units, in four five-story buildings. Each of those buildings will have retail uses on its street level.

Oldrich Foucek, chairman of the planning commission, asked about residents having views of the Lehigh from apartments blocked by taller commercial buildings that will stand closer to the river. “We haven’t counted, but a certain number of the units will have a direct view of the river,” said Keppel. “Others will have an oblique view.”

Keppel said the mixed-use property primarily is designed for commercial use. He said 63 percent of the total floor area will be for office use, while residential will be 22 percent and 15 percent will be for retail and restaurants. “We want enough residential units to make a community,” he said.

The city requires that 10 percent of the property be open space. Keppel said the project exceeds that requirement, with nearly four of the 25.68 acres designated for open space.

The property includes about 2,700 feet of Lehigh River frontage, which Keppel called “very valuable and a great public amenity.”

Public plazas will be at the foot of Allen and Furnace streets and a 12-foot wide public walkway will run all along the riverfront.

Keppel said the project’s illuminated riverfront path will be a lushly landscaped linear park. He said most or all of the trees that now stand along the riverbank probably will be removed and replaced.

In places a smaller path will descend the riverbank to get close to the water’s edge.

Two floating docks also are planned, one at the foot of Allen Street, the other at the northern part of the property, near where the planned American Parkway bridge will cross the Lehigh. The developers said boating facilities will be provided at those docks.

Open space also will be beneath the Tilghman Street bridge. Keppel said the “beautifully proportioned” arched bridge is very tall, with a spacious area beneath it, “which makes it pretty interesting from an architect’s point of view.”

In the developers’ news release, Dunn said the project will generate renewed appreciation for the Lehigh River, by creating public accessibility to the river.